Management device, cryptocurrency system, and system

ABSTRACT

[Problem] Provided are a management device and a cryptocurrency system capable of smoothly operating an entire system by detecting fraud on cryptocurrencies without using enormous calculation amounts. 
     [Solution] A management device connected to a plurality of user devices via a network, the management device including: an issued information storage area that stores a cryptocurrency ID of an issued cryptocurrency; an account information storage area that stores account information in association with one or a plurality of cryptocurrency IDs; and a history information storage area that stores history information of a cryptocurrency in association with a cryptocurrency ID.

TECHNICAL FIELD

The present invention relates to a management device, a cryptocurrencysystem, and a system.

BACKGROUND ART

There have been known cryptocurrency systems in which all transactionhistory data from the past to the present are shared among a pluralityof user devices and special hash values generated by processing calledmining are added to new transaction history data added to the sharedtransaction history data so that the falsification of the sharedtransaction history data becomes difficult (see NPL 1).

CITATION LIST Non Patent Literature

[NPL 1] free encyclopedia “Wikipedia,” Block chain, [searched on Dec. 3,2017], the Internet <URL: https://ja.wikipedia.org/wiki/

SUMMARY OF INVENTION Technical Problem

However, since calculation amounts of special hash values by miningbecome enormous in the above conventional cryptocurrency systems, theentire systems may not be smoothly operated.

Solution to Problem

The above problem can be addressed by the following means.

A management device connected to a plurality of user devices via anetwork, the management device including: an issued information storagearea that stores a cryptocurrency ID of an issued cryptocurrency; anaccount information storage area that stores account information inassociation with one or a plurality of cryptocurrency IDs; and a historyinformation storage area that stores history information of acryptocurrency in association with a cryptocurrency ID.

A management device connected to a plurality of user devices via anetwork, the management device including: an issued information storagearea that stores a cryptocurrency ID of an issued cryptocurrency; and anasset information storage area that stores an asset balance, wherein themanagement device determines propriety of issue conditions includingreception of a price of a cryptocurrency as a condition when receiving acryptocurrency issue request specifying account information from theuser devices, and stores a new cryptocurrency ID in the issuedinformation storage area when the issue conditions are met, and whereinthe management device determines propriety of buying interventionconditions including a condition in which a target price is a prescribedbuying intervention setting price or less when receiving a sell orderspecifying account information from one of the user devices, andsubtracts a price for which the buying intervention has been establishedfrom the asset balance stored in the asset information storage area whenthe buying intervention conditions are met.

Advantageous Effects of Invention

According to an embodiment of the present invention, a management devicecan detect fraud on cryptocurrencies using cryptocurrency IDs withoutusing enormous calculation amounts. Accordingly, a management device anda cryptocurrency system capable of smoothly operating an entire systemcan be provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram showing a configuration example of acryptocurrency system according to a first embodiment.

FIG. 2 is a schematic diagram showing a configuration example of themanagement device according to the first embodiment.

FIG. 3A is a schematic diagram showing an example of an issuedinformation storage area.

FIG. 3B is a schematic diagram showing an example of an accountinformation storage area.

FIG. 3C is a schematic diagram showing an example of a historyinformation storage area.

FIG. 3D is a schematic diagram showing an example of an assetinformation storage area.

FIG. 3E is a schematic diagram showing an example of a historyinformation storage area.

FIG. 4 is a sequence diagram for describing an operation example (theissue of a cryptocurrency) of the management device according to thefirst embodiment.

FIG. 5 is a sequence diagram for describing an operation example (themediation of the buying and selling of a cryptocurrency) of themanagement device according to the first embodiment.

FIG. 6 is a sequence diagram for describing an operation example (buyingintervention of a cryptocurrency) of the management device according tothe first embodiment.

FIG. 7 is a sequence diagram for describing an operation example(selling intervention of a cryptocurrency) of the management deviceaccording to the first embodiment.

FIG. 8 is a sequence for describing an operation example of acryptocurrency system according to a second embodiment.

FIG. 9 is a sequence for describing an operation example of acryptocurrency system according to a third embodiment.

DESCRIPTION OF EMBODIMENTS

[Cryptocurrency System 1 According to First Embodiment]

FIG. 1 is a schematic diagram showing a configuration example of acryptocurrency system according to a first embodiment. As shown in FIG.1, a cryptocurrency system 1 according to the first embodiment includesa management device 10 and a plurality of user devices 21 and 22connected to the management device 10 via a network 30. Hereinafter, thecryptocurrency system 1 will be described in detail.

(User Devices 21 and 22)

The user devices 21 and 22 are devices managed by users. Examples of theusers include, besides individuals and corporations, central banks,private banks, and organizations such as exchanges in all the countriesof the world. Besides desktop computers or laptop computers, smartphones or the like can be used as the user devices 21 and 22. Examplesof the network 30 that connects the management device 10 to the userdevices 21 and 22 include the Internet or the like.

(Management Device 10)

The management device 10 is a device that manages cryptocurrencies.Examples of the management include the management of issue, themanagement of buying and selling, the management of values (such as themaintenance of the values of the cryptocurrencies), and the managementof histories. Based on its centralized management of thecryptocurrencies using cryptocurrency IDs in the embodiment, themanagement device 10 can easily detect fraud on the cryptocurrencieswhile reducing calculation amounts of an entire system.

The management device 10 is managed by the managers of thecryptocurrencies. Examples of the managers include central banks,private banks, and organizations such as exchanges in all the countriesof the world. The managers do not include individuals. It does notmatter if the managers themselves directly operate the management device10 or if any person operates the management device 10 according toinstructions or the like under a commission or the like from themanagers so long as the managers take responsibility for the managementof the management device 10.

The management device 10 may be a single device or may include aplurality of devices that cooperatively operates so that a single devicecan be considered to operate. Further, the management device 10 caninclude a plurality of management devices arranged on the network 30. Inthis case, each of the plurality of management devices 10 may be asingle device or may include a plurality of devices that cooperativelyoperates so that a single device can be considered to operate.

FIG. 2 is a schematic diagram showing a configuration example of themanagement device according to the first embodiment. As shown in FIG. 2,the management device 10 has a calculation unit 12 and a storage unit14. The calculation unit 12 is, for example, a CPU, and the storage unit14 is, for example, a unit such as a RAM and a hard disk capable ofreading and writing information. The storage unit 14 may be included inthe management device 10 (see FIG. 2) or may be externally attached tothe management device 10. Further, the storage unit 14 may be a unitthat is accessed by the calculation unit 12 of the management device 10via the network 30. Each of the calculation unit 12 and the storage unit14 may be a single unit or may include a plurality of units thatcooperatively operates so that a single unit can be considered tooperate.

FIG. 3A is a schematic diagram showing an example of an issuedinformation storage area, FIG. 3B is a schematic diagram showing anexample of an account information storage area, and FIG. 3C is aschematic diagram showing an example of a history information storagearea. As shown in FIGS. 3A to 3C, the storage unit 14 of the managementdevice 10 has an issued information storage area 141 that stores thecryptocurrency IDs of issued cryptocurrencies, an account informationstorage area 142 that stores account information in association with oneor a plurality of cryptocurrency IDs, and a history information storagearea 143 that stores the history information of cryptocurrencies inassociation with cryptocurrency IDs.

(Issued Information Storage Area 141)

The issued information storage area 141 stores the cryptocurrency IDs ofissued cryptocurrencies. The cryptocurrency IDs are data unique toindividual cryptocurrencies. When one of the cryptocurrency IDs isspecified, one of the cryptocurrencies can be uniquely specified. Thecryptocurrency IDs are allocated to all the issued cryptocurrencies.

The issued information storage area 141 can store issued information inassociation with the cryptocurrency IDs. The issued informationincludes, for example, the issue prices of individual cryptocurrencies,information as to whether the prices of the cryptocurrencies have beenreceived, the dates and times of the issue of the cryptocurrencies, orthe like.

The issue prices of the individual cryptocurrencies are preferablyincreased as the number of the issued cryptocurrencies increases. Forexample, when it is assumed that three cryptocurrencies are issued, theissue price of the firstly-issued cryptocurrency is 100 yen, the issueprice of the secondly-issued cryptocurrency is 200 yen, and the issueprice of the thirdly-issued cryptocurrency is 300 yen. Thus, the earlieryou receive the issue of the cryptocurrencies, the more you can get thecryptocurrencies at a lower price, and the widespread use of thecryptocurrencies can be accelerated.

(Account Information Storage Area 142)

The account information storage area 142 stores the account informationof managers or users in association with one or a plurality ofcryptocurrency IDs. The account information is information forspecifying the issue destinations, remittance sources, or remittancedestinations of cryptocurrencies. Examples of the account informationinclude, besides account numbers, deposit addresses, or the like withwhich the cryptocurrencies are to be deposited, the information ofowners of the cryptocurrencies such as full names and designations, orthe like. Note that when the information of the owners is included inthe account information and made open to public, the owners of thecryptocurrencies are disclosed, whereby money laundering or the like canbe effectively prevented. On the other hand, when the information of theowners is not included in the account information or when theinformation of the owners is included in the account information but isnot made open to public, the issue, remittance, or the like of thecryptocurrencies is allowed but the owners are not disclosed, wherebythe anonymity of the cryptocurrencies can be maintained.

(History Information Storage Area 143)

The history information storage area 143 stores the history informationof cryptocurrencies in association with cryptocurrency IDs. Themanagement device 10 can easily detect fraud on the individualcryptocurrencies by verifying the consistency between the historyinformation stored in the history information storage area 143 with thecryptocurrency IDs. Further, the management device 10 can determinewhether the information stored in the history information storage area143 has been falsified by comparing the information stored in thehistory information storage area 143 with the information stored in theissued information storage area 141 and the information stored in theaccount information storage area 142 and determining whether there isany contradiction between the information. In making the determination,the management device 10 has no need to calculate special harsh valuesrequiring enormous calculation amounts.

Examples of the history information of the cryptocurrencies include thetypes of histories, account information associated with the histories,and the dates and times of the histories. The types of the historiesinclude, for example, information indicating that the cryptocurrencieshave been issued, information indicating that the buying and selling ofthe cryptocurrencies (for example, the remittance of thecryptocurrencies between the account numbers of the users) has beenestablished, information indicating that cryptocurrencies-buyingintervention (for example, the remittance of the cryptocurrencies fromthe account numbers of the users to the account number of the managementdevice) has been conducted, information indicating thatcryptocurrencies-selling intervention (for example, the remittance ofthe cryptocurrencies from the account number of the management device tothe account numbers of the users) has been conducted, or the like. Thus,the management device 10 can determine which of the cryptocurrencies ofthe cryptocurrency IDs have been targeted, determine which accountinformation (for example, from account information A to accountinformation B) has been used, determine which processing of the historytypes (for example, the transfer of the cryptocurrencies) has beenperformed, and determine what time the processing has been performed. InFIG. 3C, “0000” indicates the account number of a manager. Further,(out) indicates the account number of a remittance source, and (in)indicates the account number of a remittance destination. Note that theremittance indicates the transfer of the cryptocurrencies.

As described above, the storage unit 14 of the management device 10 hasthe three storage areas of the issued information storage area 141, theaccount information storage area 142, and the history informationstorage area 143. Further, each of the three storage areas stores thecryptocurrency IDs. Thus, the management device 10 can confirm whetherthe information stored in the issued information storage area 141, theinformation stored in the account information storage area 142, and theinformation stored in the history information storage area 143 have beenfalsified by comparing the information stored in the history informationstorage area 143 with the information stored in the issued informationstorage area 141 and/or the information stored in the accountinformation storage area 142 with the cryptocurrency IDs as keys anddetermining whether there is any contradiction between the informationrather than relying only on the consistency of the information stored inthe history information storage area 143. For example, when the historyinformation storage area 143 describes history information indicating asell from account information A to account information B in associationwith the cryptocurrency ID 3 but the account information storage area142 stores the account information A in association with thecryptocurrency ID 3, the management device 10 can determine that one ofthe information of the account information storage area 142 and theinformation of the history information storage area 143 may be falsifiedand suspend or stop processing on the cryptocurrency of thecryptocurrency ID 3. Further, even if one of the three storage areas isfalsified, the management device 10 is allowed to correct the falsifiedinformation into proper one using the information stored in theremaining two storage areas.

(Asset Information Storage Area 144 and Issue Number Storage Area 145)

FIG. 3D is a schematic diagram showing an example of an assetinformation storage area 144, and FIG. 3E is a schematic diagram showingan example of the history information storage area 143. As shown inFIGS. 3D and 3E, the storage unit 14 of the management device 10 canalso have the asset information storage area 144 that stores assetbalances, an issue number storage area 145 that stores the number ofissued cryptocurrencies, or the like. The asset balances are informationindicating the total of values paid from users to managers as the pricesof the cryptocurrencies. In the example shown in FIG. 3D, asset balancesassociated with the latest reception dates and times indicate the latestasset balances.

For example, when it is assumed that totally three cryptocurrencies havebeen issued in which the issue price of the first cryptocurrency is1,000 yen, the issue price of the second cryptocurrency is 1,500 yen,and the issue price of the third cryptocurrency is 2,000 yen and thatthe prices of the cryptocurrencies are paid from a user to a manager, anasset balance is, for example, 4,500 yen and the number of the issuedcryptocurrencies is, for example, three. Note that the prices of thecryptocurrencies are values set according to the issue prices of thecryptocurrencies and equal, for example, the issue prices of thecryptocurrencies. Besides currencies such as yen and dollar, values suchas electric money and points can be used as the prices.

In the asset balances, the prices of the cryptocurrencies, the accountinformation of users having paid the prices of the cryptocurrencies,reception dates and times at which the prices have been received, or thelike can be stored in association with each other. Thus, the managementdevice 10 can easily specify who has paid the prices, when the priceshave been paid, and how much the prices have been paid. For example,when the prices have been already received or when it is expected thatthe prices will be reliably received, the management device 10 can addthe prices of issue to the asset balances. Further, the managementdevice 10 can store the prices and the account information of users inassociation with the asset balances after the addition.

Each of the storage areas described above may be a physically singlestorage area or may include a plurality of storage areas handled as asubstantially single area when the calculation unit 12 performsprescribed processing.

In the embodiment as well, hash values having large calculation amountsmay be generated using all information from the past to the presentstored in the storage areas as in mining and contained in informationthat is to be newly stored in the storage areas. Thus, the falsificationof the information stored in the storage areas can be further prevented.However, according to the embodiment, fraud on the cryptocurrencies canbe detected without relying on a falsification prevention device thatuses such hash values having large calculation amounts as describedabove. Accordingly, even when hash values are used, it is preferable touse hash values having small calculation amounts or the like rather thanusing hash values having large calculation amounts.

(Operation Example of Management Device 10: Issue of Cryptocurrency)

FIG. 4 is a sequence diagram for describing an operation example (theissue of a cryptocurrency) of the management device according to thefirst embodiment. Hereinafter, a description will be given, withreference to FIG. 4, of an operation example of the management device 10in a case in which a cryptocurrency is issued to the user device 21.

(Step S11)

First, the management device 10 receives a cryptocurrency issue requestspecifying account information from the user device 21. Thus, the issueof a cryptocurrency is requested from the user device 21 to a manager.The cryptocurrency issue request may specify a desired issue number,besides the account information.

(Step S12)

When the manager receives the price of the cryptocurrency from a user,the management device 10 preferably adds the price to an asset balancein the asset information storage area 144 of the storage unit 14 (stepS12). Thus, the issue of the cryptocurrency and the asset balance of themanager can be accurately linked to each other. Further, buyingintervention that will be described later can be prevented from beingunlimitedly performed. Note that this step may be performed before thereception of the price or after cryptocurrency issue processing.

(Steps S13 and S14)

Next, the management device 10 determines the propriety of issueconditions including the receiving condition of the price of thecryptocurrency (step S13), and performs the cryptocurrency issueprocessing (step S14) when the issue conditions are met. Provided thatthe price is received, the value of the cryptocurrency can be stabilizedwith the price regarded as the support of the value of thecryptocurrency. Further, the buying intervention that will be describedlater can be limited.

The propriety of the receiving condition can be determined based onwhether the price of the cryptocurrency has been already received orwhether it is expected that the price will be reliably received.Specific modes for the determination are not particularly limited.However, the determination can be made based on whether the price hasbeen stored in the asset information storage area 144 in associationwith the account information specified by the cryptocurrency issuerequest, a numeric value indicating the credibility of the user, whetherthe user corresponds to a user stored in the storage unit 14 in advanceas a person with the credibility, whether it can be evaluated that theprice of the cryptocurrency has been substantially received, or thelike.

In addition, the issue conditions preferably include a condition inwhich the number of issued cryptocurrencies stored in the issue numberstorage area 145 is a prescribed upper limit value or less, or acondition in which, when a desired issue number of N (N≥2) is specifiedby the cryptocurrency issue request, the sum of the number of the issuedcryptocurrencies stored in the issue number storage area 145 and thedesired issue number is a prescribed upper limit value or less. Theprescribed upper limit value is determined according to market trends.

Moreover, the issue conditions preferably include a condition in whichthe market price of the cryptocurrency is an issue price or more. Thus,the number (supply amount) of the issued cryptocurrencies is limitedaccording to the market price, whereby the value of the cryptocurrencycan be easily maintained. The market price is transmitted to themanagement device 10 from, for example, a server or the like on thenetwork 30.

Hereinafter, a description will be given of the cryptocurrency issueprocessing (step S14).

(Step S141)

First, the management device 10 stores a new cryptocurrency ID in theissued information storage area 141. Thus, the new cryptocurrency ID isissued, and the fact that the new cryptocurrency ID has been issued isrecorded on the management device 10. This step includes, besides a casein which the new cryptocurrency ID is actually stored in the issuedinformation storage area 141, a case in which the information of theissued information storage area 141 is so updated that an unissuedcryptocurrency ID having been already stored in the issued informationstorage area 141 will be handled as an issued cryptocurrency ID. The newcryptocurrency ID used to be actually stored in the former case maybegenerated by the management device 10 on a case-by-case basis in thisstep. Alternatively, usable unissued cryptocurrency IDs maybe stored inadvance in the storage unit 14 or the like of the management device 10,so that the management device 10 selects one of the IDs randomly orbased on a prescribed rule on a case-by-case basis.

(Step S142)

Next, the management device 10 stores the new cryptocurrency ID in theaccount information storage area 142 in association with the accountinformation specified by the cryptocurrency issue request. Thus, theowner of the newly-issued cryptocurrency is recorded on the managementdevice 10.

(Step S143)

Then, the management device 10 stores the new cryptocurrency ID andhistory information indicating that the cryptocurrency has been newlyissued in the history information storage area in association with eachother. Thus, the fact that the cryptocurrency has been newly issued isrecorded on the management device 10.

(Step S144)

The management device 10 preferably increments the number of the issuedcryptocurrencies stored in the issue number storage area 145. Thus, thenumber of the issued cryptocurrencies can be managed, whereby thelimitation of the number of the issued cryptocurrencies is madepossible. The management device 10 increments the number of the issuedcryptocurrencies by one when the desired number of the issuedcryptocurrencies is not specified by the cryptocurrency issue request orwhen 1 is specified as the desired number of the cryptocurrencies by thecryptocurrency issue request. Further, when a desired issue number of N(N≥2) is specified by the cryptocurrency issue request, the managementdevice 10 increments the number of the issued cryptocurrencies by N.

(Step S145)

The management device 10 preferably transmits a cryptocurrency issuenotification to the user device 21. Thus, the user of the user device 21is notified of the issue of the cryptocurrency.

(Mediation of Buying and Selling of Cryptocurrency)

FIG. 5 is a sequence diagram for describing an operation example (themediation of the buying and selling of a cryptocurrency) of themanagement device according to the first embodiment. Hereinafter, adescription will be given, with reference to FIG. 5, of an operationexample of the management device 10 in a case in which the buying andselling of a cryptocurrency is performed between the user devices 21 and22.

(Steps S21 and S22)

First, the management device 10 receives a sell order specifying accountinformation from the user device 21 (step S21) and receives a buy orderspecifying account information from the user device 22 (step S22). Thus,the user device 21 requests the management device 10 to sell acryptocurrency, and the user device 22 requests the management device 10to buy the cryptocurrency. The sell order may specify a desired sellnumber, besides the account information. The buy order may specify adesired buy number, besides the account information.

(Steps S23 and S24)

Next, the management device 10 determines the propriety of buying andselling mediating conditions including conditions in which the accountinformation specified by the sell order is stored in the accountinformation storage area 142 so as to be associated, a cryptocurrency IDstored in the account information storage area 142 in association withthe account information specified by the sell order is stored in theissued information storage area 141, and the cryptocurrency ID stored inthe account information storage area 142 in association with the accountinformation specified by the sell order is stored in the historyinformation storage area 143 in association with history information(step S23). When the conditions are met, the management device 10performs buying and selling mediating processing (step S24) with thedetermination that the buying and selling of the cryptocurrency IDstored in the account information storage area 142 in association withthe account information specified by the sell order is established. Whena plurality of cryptocurrency IDs is stored in the account informationstorage area 142 in association with the account information specifiedby the sell order, the management device 10 can perform the buying andselling mediating processing (step S24) on one cryptocurrency ID or aplurality of cryptocurrency IDs with the determination that the buyingand selling for the one cryptocurrency ID or the plurality ofcryptocurrency IDs is established. Hereinafter, a description will begiven of the buying and selling mediating processing (step S24).

(Step S241)

First, the management device 10 deletes, from the account informationstorage area 142, the account information specified by the sell orderand the cryptocurrency ID for which the buying and selling has beenestablished, and stores the account information specified by the buyorder and the cryptocurrency ID for which the buying and selling hasbeen established in the account information storage area 142 inassociation with each other (step S241). Thus, the cryptocurrency istransferred from the user of the user device 21 acting as a seller tothe user of the user device 21 acting as a buyer (remittance iscompleted), and the fact that the cryptocurrency has been transferred isrecorded on the management device 10.

(Step S242)

Next, the management device 10 stores the cryptocurrency ID for whichthe buying and selling has been established and history informationindicating that the buying and selling of the cryptocurrency has beenestablished in the history information storage area 143 in associationwith each other. Thus, the fact that the buying and selling (remittance)of the cryptocurrency has been established is recorded on the managementdevice 10.

(Steps S243 and S244)

The management device 10 preferably transmits a buying and sellingestablishment notification to the user devices 21 and 22. Thus, theusers of the user devices 21 and 22 are notified of the establishment ofthe buying and selling of the cryptocurrency.

(Cryptocurrency Buying Intervention)

FIG. 6 is a sequence diagram for describing an operation example (buyingintervention processing) of the management device according to the firstembodiment. Hereinafter, a description will be given, with reference toFIG. 6, of an operation example of the management device 10 in a case inwhich the management device 10 performs buying intervention.

(Step S31)

First, the management device 10 receives a sell order specifying accountinformation. Thus, the user device 21 requests the manager to buy acryptocurrency. The sell order may also specify a desired sell number,besides the account information.

(Step S32)

Next, the management device 10 determines the propriety of buyingintervention conditions including conditions in which a target price isa prescribed buying intervention setting price or less, the accountinformation specified by the sell order is stored in the accountinformation storage area 142 so as to be associated, a cryptocurrency IDstored in the account information storage area 142 in association withthe account information specified by the sell order is stored in theissued information storage area 141, and the cryptocurrency ID stored inthe account information storage area 142 in association with the accountinformation specified by the sell order is stored in the historyinformation storage area 143 in association with history information(step S32). When the buying intervention conditions are met, themanagement device 10 performs buying intervention processing (step S33)with the determination that the buying intervention for thecryptocurrency ID stored in the account information storage area 142 inassociation with the account information specified by the sell order isestablished. When a plurality of cryptocurrency IDs is stored in theaccount information storage area 142 in association with the accountinformation specified by the sell order, the management device 10 canperform the buying intervention processing (step S33) on onecryptocurrency ID or a plurality of cryptocurrency IDs with thedetermination that the buying intervention for the one cryptocurrency IDor the plurality of cryptocurrency IDs is established. Thus, themanagement device 10 is allowed to automatically perform the buyingintervention processing (without someone's help) according to theestablishment of prescribed conditions and can promptly and accuratelyprevent drop in the price of the cryptocurrency. Hereinafter, adescription will be given of the buying intervention processing (stepS33).

The buying intervention conditions preferably include conditions inwhich an asset balance stored in an asset balance stored in the assetinformation storage area 144 is a target price or more, or, when adesired sell number of N (N≥2) is specified by the sell order, the assetbalance stored in the asset information storage area 144 is the productof the desired sell number and the target price or more. Thus, thebuying intervention processing can be performed within the range of theasset balance of the manager. Accordingly, the buying intervention canbe prevented from being unlimitedly performed.

The target price may be, for example, the market price of thecryptocurrency transmitted from a server or the like on the network 30to the management device 10 or a sell order price specified by the sellorder. The buying intervention setting price is, for example, input inadvance to the management device 10 by the manager and stored in thestorage unit 14 of the management device 10.

(Step S331)

First, the management device 10 deletes, from the account informationstorage area 142, the account information specified by the sell orderand the cryptocurrency ID for which the buying intervention has beenestablished, and stores the account information of the management device10 and the cryptocurrency ID for which the buying intervention has beenestablished in the account information storage area 142 in associationwith each other (step S331) . Thus, the cryptocurrency is transferredfrom the user of the user device 21 acting as a seller to the manageracting as a buyer, and the fact that the cryptocurrency has beentransferred is recorded on the management device 10.

(Step S332)

Next, the management device 10 stores the cryptocurrency ID for whichthe buying intervention has been performed and history informationindicating that the buying intervention has been performed in thehistory information storage area 143 in association with each other.Thus, the fact that the buying intervention for the cryptocurrency hasbeen performed is recorded on the management device 10.

(Step S333)

The management device 10 preferably subtracts a price for which thebuying intervention has been established from the asset balance storedin the asset information storage area 144 (step S333). When a desiredsell number of N (N≥2) is specified by the sell order, the managementdevice 10 subtracts the product of the desired sell number and the pricefor which the buying intervention has been established from the assetbalance stored in the asset information storage area 144. Thus, theasset balance of the manager can be accurately managed.

(Step S334)

The management device 10 preferably transmits a buying and sellingestablishment notification to the user device 21. Thus, the user of theuser device 21 is notified of the establishment of the buying andselling of the cryptocurrency.

(Cryptocurrency Selling Intervention)

FIG. 7 is a sequence diagram for describing an operation example(selling intervention processing) of the management device according tothe first embodiment. Hereinafter, a description will be given, withreference to FIG. 7, of an operation example of the management device 10in a case in which the management device 10 performs sellingintervention.

(Step S41)

First, the management device 10 receives a buy order specifying accountinformation from the user device 21. Thus, the user device 21 requeststhe manager to buy a cryptocurrency. The buy order may also specify adesired buy number, besides the account information.

(Steps S42 and S43)

Next, the management device 10 determines the propriety of sellingintervention conditions including a condition in which a target price isa prescribed selling intervention setting price or more (step S42). Whenthe selling intervention conditions are met, the management device 10performs selling intervention processing (step S43) with thedetermination that the selling intervention for a cryptocurrency IDstored in the account information storage area 142 in association withthe account information of the management device 10 is established. Whena plurality of cryptocurrency IDs is stored in the account informationstorage area 142 in association with the account information of themanagement device 10, the management device 10 can perform the sellingintervention processing (step S43) on one cryptocurrency ID or aplurality of cryptocurrency IDs with the determination that the sellingintervention for the one cryptocurrency ID or the plurality ofcryptocurrency IDs is established. Thus, the management device 10 isallowed to automatically perform the selling intervention processing(without someone's help) according to the establishment of prescribedconditions. Hereinafter, a description will be given of the sellingintervention processing (step S43).

The selling intervention conditions further preferably include acondition in which the target price is the issue price of acryptocurrency, which is stored in the issued information storage areain association with the cryptocurrency ID of the finally-issuedcryptocurrency, or more.

The target price may be, for example, the market price of thecryptocurrency transmitted from a server or the like on the network 30to the management device, or a buy order price specified by the buyorder. The selling intervention setting price is, for example, input inadvance to the management device 10 by the manager and stored in thestorage unit 14 of the management device 10.

(Step S431)

First, the management device 10 deletes, from the account informationstorage area 142, the account information of the management device 10and the cryptocurrency ID for which the selling intervention has beenestablished, and stores the account information specified by the buyorder and the cryptocurrency ID for which the buying and selling hasbeen established in the account information storage area 142 inassociation with each other. Thus, the cryptocurrency is transferredfrom the manager acting as a seller to the user of the user device 21 asa buyer, and the fact that the cryptocurrency has been transferred isrecorded on the management device 10.

(Step S432)

Next, the management device 10 stores the cryptocurrency ID for whichthe selling intervention has been established and history informationindicating that the selling intervention has been performed in thehistory information storage area 143 in association with each other.Thus, the fact that the selling intervention for the cryptocurrency hasbeen performed is recorded on the management device 10.

(Step S433)

The management device 10 preferably adds a price for which the sellingintervention has been established to an asset balance stored in theasset information storage area 144. Thus, the asset balance of themanager can be accurately managed.

(Step S434)

The management device 10 preferably transmits a buying and sellingestablishment notification to the user device 21. Thus, the user of theuser device 21 is notified of the establishment of the buying andselling of the cryptocurrency.

According to the first embodiment described above, fraud oncryptocurrencies can be detected using cryptocurrency IDs without usingenormous calculation amounts. Accordingly, the management device 10 andthe cryptocurrency system 1 capable of smoothly operating an entiresystem can be provided.

Further, according to the buying and selling mediating conditions andthe buying intervention conditions of the embodiment, the unauthorizedbuying and selling of cryptocurrencies and the incorrect exercise ofbuying intervention can be prevented. That is, provided that accountinformation specified by sell orders is stored in the accountinformation storage area 142 so as to be associated, the unauthorizedselling of cryptocurrencies by persons having no account information canbe prevented. Further, provided that cryptocurrency IDs stored inassociation with account information specified by sell orders are storedin the issued information storage area 141, the selling of unissuedcryptocurrencies can be prevented. Further, provided that cryptocurrencyIDs stored in association with account information specified by sellorders are stored in the history information storage area 143 inassociation with history information, the unauthorized selling ofcryptocurrencies having no history information (for example,cryptocurrencies having not been issued) can be prevented. Further,since conditions are not met when fraud is found in any one of the threestorage areas, the implementation of buying and selling mediatingprocessing and buying intervention processing in a case in which thefalsification of the information of any one of the three storage areascan be effectively prevented.

Since existing cryptocurrencies as represented by bit coins do not havethe function of maintaining their values, the prices of thecryptocurrencies may sharply drop. However, according to the embodiment,cryptocurrencies are issued in trade for prices. Therefore,cryptocurrencies having the function of maintaining their values can becreated. Further, the values of cryptocurrencies can be secured by thedetection of fraud in the mediation of buying and selling. In addition,sharp drops in values can be directly prevented by the implementation ofbuying intervention. Thus, according to the embodiment, a valuemaintaining function is assigned to issued cryptocurrencies as one ofelements needed as widely-circulating currencies, wherebycryptocurrencies having secured values can be provided.

According to the embodiment, the management device 10 (a managementdevice 51 belonging to, for example, a top layer that will be describedlater in a case in which a plurality of management devices 10 isconnected to the network 30; hereinafter, the same applies to thisparagraph) on the network 30 is regarded as a central bank, and uniquecryptocurrencies can be issued from the management device 10 regarded asthe central bank. As for currently-mainstream cryptocurrencies, sinceminers consuming CPU time, power, and personnel costs receive prices forthe issue of the cryptocurrencies based on the concept of mining, thereare no values supporting the values of the cryptocurrencies themselves.On the other hand, according to the embodiment, with the issue orcirculation of cryptocurrencies issued by the management device 10, CPUtime, power, and personnel costs can be effectively reduced. Further,cryptocurrencies issued by the management device 10 are distributed intothe markets when users such as individuals and corporations exchangeother currencies. As a result, asset balances (foreign currencyreserves) are accumulated in the asset information storage area of themanagement device 10 simultaneously with the issue. With theaccumulation of the asset balances (foreign currency reserves), themanagement device 10 can buy the cryptocurrencies (buying intervention)from the markets when the market prices of the cryptocurrencies issuedby the management device 10 itself drop. Further, according to theembodiment, sharp drops in the prices are easily reduced compared withother cryptocurrencies in such a way that the issue prices are risen foreach issue of the cryptocurrencies. Further, according to theembodiment, the prices of the cryptocurrencies can be based on thesupply and demand of the markets, the number of the issuedcryptocurrencies is automatically set based on market prices, and laborforces needed to maintain systems can be reduced. The manager canreceive various prices such as dollar, euro, SDR, yen, yuan, and poundin return for the cryptocurrencies by the management device 10, andthese prices are added to asset balances. Such asset balances haveproperties as foreign currency reserves and have the function ofmaintaining values in the cryptocurrencies.

[Cryptocurrency System 2 According to Second Embodiment]

FIG. 8 is a sequence for describing an operation example of acryptocurrency system according to a second embodiment. As shown in FIG.8, a management device 10 in a cryptocurrency system 2 according to thesecond embodiment determines the propriety of issue conditions includingthe receiving condition of the price of a cryptocurrency (step S52) whenreceiving a cryptocurrency issue request specifying account informationfrom a user device 21 (step S51). When the issue conditions are met, themanagement device 10 stores a new cryptocurrency ID in an issuedinformation storage area 141 (step S53). Further, the management device10 determines the propriety of buying intervention conditions includinga condition in which a target price is a prescribed buying interventionsetting price or less (step S55) when receiving a sell order specifyingaccount information from the user device 21 (step S54). When the buyingintervention conditions are met, the management device 10 subtracts aprice for which the buying intervention has been established from anasset balance stored in an asset information storage area 144 (stepS56). The management device 10 preferably transmits a buying and sellingestablishment notification to the user device 21 after the completion ofstep S56 (step S56). According to the second embodiment, the managementdevice 10 is allowed to automatically perform buying interventionprocessing (without someone's help) when prescribed conditions are metand thus can promptly and accurately prevent sharp drops in the pricesof cryptocurrencies.

[Cryptocurrency System 3 According to Third Embodiment]

FIG. 9 is a sequence for describing an operation example of acryptocurrency system according to a third embodiment. As shown in FIG.9, a cryptocurrency system 3 according to the third embodiment is acryptocurrency system including a plurality of management devices 51 to57 hierarchized in a tree form and connected to each other. A managementdevice belonging to one hierarchy includes an issued information storagearea for the own device and issued information storage areas for otherdevices. The issued information storage areas for other devices storeinformation stored in issued information storage areas for own devicesprovided in management devices belonging to a hierarchy immediatelybelow the one hierarchy. That is, the information is shared (orsynchronized) between the issued information storage areas for otherdevices and the issued information storage areas for the own devicesprovided in the management devices belonging to the hierarchyimmediately below the one hierarchy. The management devices 52 and 53belonging to a second hierarchy are connected immediately below themanagement device 51 belonging to a first hierarchy, and the managementdevices 54, 55, 56, and 57 belonging to a third hierarchy are connectedimmediately below the management device 52 belonging to the secondhierarchy.

Specifically, the management device 51 in the top layer includes anissued information storage area A for the own device and issuedinformation storage areas B and C for other devices. Further, themanagement device 52 belonging to the second hierarchy includes anissued information storage area B for the own device and issuedinformation storage areas D, E, F, and G for other devices . Further,the management device 53 belonging to the second hierarchy includes anissued information storage area C for the own device and issuedinformation storage areas H, I, J, and K for other devices . Further,the management devices 54, 55, 56, and 57 belonging to the thirdhierarchy respectively include issued information storage areas D, E, F,and G for the own devices and issued information storage areas for otherdevices. The issued information storage areas B and C for other devicesprovided in the management device 51 in the top layer store informationstored in the issued information storage areas B and C for the owndevices provided in the management devices 52 and 53 belonging to thesecond hierarchy and connected immediately below the management device51 belonging to the top layer. Further, the issued information storageareas D, E, F, and G for other devices provided in the management device52 belonging to the second hierarchy respectively store informationstored in the issued information storage areas D, E, F, and G for theown devices provided in the management devices 54, 55, 56, and 57belonging to the third hierarchy and connected immediately below themanagement device 52 belonging to the second hierarchy.

According to the third embodiment, since a user device is allowed toperform the transmission of a cryptocurrency issue request, thetransmission of a sell order or a buy order, or the like to any of theplurality of management devices 51 to 57, traffic loads in thecryptocurrency system 3 can be dispersed. Further, since issuedinformation storage areas are shared between a management devicebelonging to one hierarchy and management devices belonging to ahierarchy immediately below the one hierarchy, fraud can be easilydetected by comparing contents stored in issued information storageareas for other devices provided in the management device belonging tothe one hierarchy with contents stored in issued information storageareas for own devices provided in the management devices belonging tothe hierarchy below the one hierarchy and determining whether theymatch.

Note that although their illustrations and detailed descriptions areomitted, an account information storage area and a history informationstorage area can also be shared (or synchronized) between a managementdevice belonging to one hierarchy and management devices belonging to ahierarchy immediately below the one hierarchy like the case of theissued information storage area.

In the third embodiment, writing and reading information in and from atleast one of: issued information storage areas for own devices; accountinformation storage areas for own devices; and history informationstorage areas for own devices may be prohibited, and writing and readinginformation in and from at least one of: issued information storageareas for other devices; account information storage areas for otherdevices; and history information storage areas for other devices may beprohibited. Thus, the functions of management devices belonging to lowerhierarchies can be limited according to the rights of the managers ofthe management devices belonging to the lower hierarchies. Therefore, ina case in which the managers of the management devices belonging to thelower hierarchies have rights to mediate buying and selling but do nothave rights to issue cryptocurrencies or the like, the functions of themanagement devices belonging to the lower hierarchies can beappropriately limited.

The plurality of management devices 51 to 57 may be directly connectedto each other, may be connected to each other via other devices, or maybe connected to each other via networks such as the Internet anddedicated lines.

[Other]

In the specification, the transmission or reception of one request orone order specifying one information indicates, for example, a case inwhich the one information is received before and/or after the receptionof the one request in association with the one request, a case in whichthe one information itself is not received but the one information canbe specified from the received one request, or the like, besides a casein which the one request or the one order including the one informationitself is received.

Further, in the specification, the deletion of one information, onedata, or the like stored in one area indicates a case in which theinformation, the data, or the like is invalidated without being deletedin the area to be substantially deleted (for example, a case in whichother information or other data indicating invalidity is stored in arecord (row) or the like in which the information, the data, or the likeis stored), besides a case in which the information, the data, or thelike is actually deleted from the area (for example, a case in which arecord (row) in which the information, the data, or the like is storedis actually deleted).

Further, in the specification, one request, one order, or the like maybe sent and received as one data, or may be sent and received as aplurality of divided data items. Further, one request, one order, or thelike may be sent and received at a time, or may be separately sent andreceived a plurality of times. Further, one request, one order, or thelike maybe singly sent and received, or may be sent together with otherinformation. For example, the one request, the one order, or the likemay be sent and received in such a way that information such as a headeris added to the one request, the one order, or the like to constituteone or a plurality of packets and the one or the plurality of packets issent and received.

Central banks, private banks, or the like in all the countries canfurther issue new cryptocurrencies or real currencies of which thevalues are supported by cryptocurrencies issued by the management device10.

The descriptions of the embodiments are given above, but configurationsin the claims are not limited to the descriptions.

REFERENCE SIGNS LIST

-   1, 2, 3 Cryptocurrency system-   10 Management device-   12 Calculation unit-   14 Storage unit-   141 Issued information storage area-   142 Account information storage area-   143 History information storage area-   144 Asset information storage area-   145 Issue number storage area-   21, 22 User device-   30 Network-   51 to 57 Management device

1.-12. (canceled)
 13. A management device connected to a plurality ofuser devices via a network, the management device comprising: an issuedinformation storage area that stores a cryptocurrency ID of an issuedcrypto currency; an account information storage area that stores accountinformation in association with one or a plurality of cryptocurrencyIDs; and a history information storage area that stores historyinformation of a cryptocurrency in association with a cryptocurrency ID,wherein, when receiving a sell order specifying account information fromone of the user devices and a buy order specifying account informationfrom another of the user devices, the management device determinespropriety of buying and selling mediating conditions includingconditions in which the account information specified by the sell orderis stored in the account information storage area, a cryptocurrency IDstored in the account information storage area in association with theaccount information specified by the sell order is stored in the issuedinformation storage area, and the cryptocurrency ID stored in theaccount information storage area in association with the accountinformation specified by the sell order is stored in the historyinformation storage area in association with history information, andwhen the buying and selling mediating conditions are met, the managementdevice performs buying and selling mediating processing with adetermination that buying and selling for the cryptocurrency ID storedin the account information storage area in association with the accountinformation specified by the sell order is established, and the buyingand selling mediating processing includes a step of deleting, from theaccount information storage area, the account information specified bythe sell order and the cryptocurrency ID for which the buying andselling has been established, and storing the account informationspecified by the buy order and the cryptocurrency ID for which thebuying and selling has been established in the account informationstorage area in association with each other, and a step of storing thecryptocurrency ID for which the buying and selling has been establishedand history information indicating that the buying and selling of thecryptocurrency has been established in the history information storagearea in association with each other.
 14. The management device accordingto claim 13, wherein, when receiving a sell order specifying accountinformation from one of the user devices, the management devicedetermines propriety of buying intervention conditions includingconditions in which a target price is a prescribed buying interventionsetting price or less, the account information specified by the sellorder is stored in the account information storage area, acryptocurrency ID stored in the account information storage area inassociation with the account information specified by the sell order isstored in the issued information storage area, and the cryptocurrency IDstored in the account information storage area in association with theaccount information specified by the sell order is stored in the historyinformation storage area in association with history information, andwhen the buying intervention conditions are met, the management deviceperforms buying intervention processing with a determination that buyingintervention for the cryptocurrency ID stored in the account informationstorage area in association with the account information specified bythe sell order is established, and the buying intervention processingincludes a step of deleting, from the account information storage area,the account information specified by the sell order and thecryptocurrency ID for which the buying intervention has beenestablished, and storing account information of the management deviceand the cryptocurrency ID for which the buying intervention has beenestablished in the account information storage area in association witheach other, and a step of storing the cryptocurrency ID for which thebuying intervention has been established and history informationindicating that the buying intervention has been performed in thehistory information storage area in association with each other.
 15. Themanagement device according to claim 14, wherein the buying interventionconditions include a condition in which an asset balance stored in anasset information storage area is the target price or more, or acondition in which, when a desired sell number of N (N≥2) is specifiedby the sell order, the asset balance stored in the asset informationstorage area is a product of the desired sell number and the targetprice or more, and the buying intervention processing includes a step ofsubtracting the target price from the asset balance stored in the assetinformation storage area, or a step of, when a desired sell number of N(N≥2) is specified by the sell order, subtracting the product of thedesired sell number and the target price from the asset balance storedin the asset information storage area.
 16. A management device connectedto a plurality of user devices via a network, the management devicecomprising: an issued information storage area that stores acryptocurrency ID of an issued crypto currency; an account informationstorage area that stores account information in association with one ora plurality of cryptocurrency IDs; and a history information storagearea that stores history information of a cryptocurrency in associationwith a cryptocurrency ID, wherein, when receiving a sell orderspecifying account information from one of the user devices, themanagement device determines propriety of buying intervention conditionsincluding conditions in which a target price is a prescribed buyingintervention setting price or less, the account information specified bythe sell order is stored in the account information storage area, acryptocurrency ID stored in the account information storage area inassociation with the account information specified by the sell order isstored in the issued information storage area, and the cryptocurrency IDstored in the account information storage area in association with theaccount information specified by the sell order is stored in the historyinformation storage area in association with history information, andwhen the buying intervention conditions are met, the management deviceperforms buying intervention processing with a determination that buyingintervention for the cryptocurrency ID stored in the account informationstorage area in association with the account information specified bythe sell order is established, and the buying intervention processingincludes a step of deleting, from the account information storage area,the account information specified by the sell order and thecryptocurrency ID for which the buying intervention has beenestablished, and storing account information of the management deviceand the cryptocurrency ID for which the buying intervention has beenestablished in the account information storage area in association witheach other, and a step of storing the cryptocurrency ID for which thebuying intervention has been established and history informationindicating that the buying intervention has been performed in thehistory information storage area in association with each other.
 17. Themanagement device according to claim 16, wherein the buying interventionconditions include a condition in which an asset balance stored in anasset information storage area is the target price or more, or acondition in which, when a desired sell number of N (N≥2) is specifiedby the sell order, the asset balance stored in the asset informationstorage area is a product of the desired sell number and the targetprice or more, and the buying intervention processing includes a step ofsubtracting the target price from the asset balance stored in the assetinformation storage area, or a step of, when a desired sell number of N(N≥2) is specified by the sell order, subtracting the product of thedesired sell number and the target price from the asset balance storedin the asset information storage area.
 18. The management deviceaccording to claim 13, wherein, when receiving a cryptocurrency issuerequest specifying account information from the user devices, themanagement device determines propriety of issue conditions includingreception of a price of a cryptocurrency as a condition, and when theissue conditions are met, the management device performs cryptocurrencyissue processing, and the cryptocurrency issue processing includes astep of storing a new cryptocurrency ID in the issued informationstorage area, a step of storing the new cryptocurrency ID in the accountinformation storage area in association with the account informationspecified by the cryptocurrency issue request, and a step of storing thenew cryptocurrency ID in the history information storage area inassociation with history information indicating that the cryptocurrencyhas been newly issued.
 19. The management device according to claim 18,further comprising: an issue number storage area that stores the numberof issued cryptocurrencies, wherein the issue conditions include acondition in which the number of the issued cryptocurrencies stored inthe issue number storage area is a prescribed upper limit value or less,or a condition in which, when a desired issue number of N (N≥2) isspecified by the cryptocurrency issue request, a sum of the number ofthe issued cryptocurrencies stored in the issue number storage area andthe desired issue number is the prescribed upper limit value or less.20. The management device according to claim 13 wherein, when receivinga buy order specifying account information from one of the user devices,the management device determines propriety of selling interventionconditions including a condition in which a target price is a prescribedselling intervention setting price or more, and when the sellingintervention conditions are met, the management device performs sellingintervention processing with a determination that selling interventionfor a cryptocurrency ID stored in the account information storage areain association with the account information of the management device isestablished, and the selling intervention processing includes a step ofdeleting, from the account information storage area, the accountinformation of the management device and the cryptocurrency ID for whichthe selling intervention has been established, and storing the accountinformation specified by the buy order and the cryptocurrency ID forwhich the selling intervention has been established in the accountinformation storage area in association with each other, and a step ofstoring the cryptocurrency ID for which the selling intervention hasbeen established and history information indicating that the sellingintervention has been performed in the history information storage areain association with each other.
 21. A cryptocurrency system comprising:the management device according to claim 13; a plurality of user devicesconnected to the management device via a network.
 22. A cryptocurrencysystem comprising: the management device according to claim 13 providedin plurality, the management devices being hierarchized in a tree formand connected to each other, wherein the management devices belonging toone hierarchy include the respective issued information storage areasfor the own devices, the respective account information storage areasfor the own devices, and the respective history information storageareas for the own devices, and the respective issued information storageareas for other devices, the respective account information storageareas for other devices, and the respective history information storageareas for other devices, and the issued information storage areas forother devices, the account information storage areas for other devices,and the history information storage areas for other devices provided inthe management devices belonging to the one hierarchy respectively storeinformation stored in the issued information storage areas for the owndevices, information stored in the account information storage areas forthe own devices, and information stored in the history informationstorage areas for the own devices of the management devices belonging toa hierarchy immediately below the one hierarchy.
 23. The cryptocurrencysystem according to claim 22, wherein the management devices areprohibited from writing and/or reading information in and from at leastone of: the issued information storage areas for the own devices; theaccount information storage areas for the own devices; and the historyinformation storage areas for the own devices, and prohibited fromwriting and/or reading information in and from at least one of: theissued information storage areas for other devices; the accountinformation storage areas for other devices; and the history informationstorage areas for other devices.
 24. A cryptocurrency system comprising:management devices hierarchized in a tree form and connected to eachother, wherein the management devices are connected to a plurality ofuser devices via a network, and each include an issued informationstorage area that stores a cryptocurrency ID of an issuedcryptocurrency, an account information storage area that stores accountinformation in association with one or a plurality of cryptocurrencyIDs, and a history information storage area that stores historyinformation of a cryptocurrency in association with a cryptocurrency ID,and wherein the management devices belonging to one hierarchy includethe respective issued information storage areas for the own devices, therespective account information storage areas for the own devices, andthe respective history information storage areas for the own devices,and the respective issued information storage areas for other devices,the respective account information storage areas for other devices, andthe respective history information storage areas for other devices, andthe issued information storage areas for other devices, the accountinformation storage areas for other devices, and the history informationstorage areas for other devices provided in the management devicesbelonging to the one hierarchy respectively store information stored inthe issued information storage areas for the own devices, informationstored in the account information storage areas for the own devices, andinformation stored in the history information storage areas for the owndevices of the management devices belonging to a hierarchy immediatelybelow the one hierarchy.
 25. The cryptocurrency system according toclaim 24, wherein the management devices are prohibited from writingand/or reading information in and from at least one of: the issuedinformation storage areas for the own devices; the account informationstorage areas for the own devices; and the history information storageareas for the own devices, and prohibited from writing and/or readinginformation in and from at least one of: the issued information storageareas for other devices; the account information storage areas for otherdevices; and the history information storage areas for other devices.